ECO2024: Unease About BMI Defining Clinical Obesity

The symposium that packed an auditorium at ECO2024 yesterday dealt with the fundamental need to get beyond BMI for defining clinical obesity. It seems so simple. “Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health,” says the World Health Organization.

And yet that definition ties back to BMI for an understanding of what is excessive. Furthermore, it goes on to define obesity in terms of “increased risk for many NCDs” – not as an illness in its own right. Reporting on the work of the Lancet Commission on Clinical Obesity, Francesco Rubino said yesterday that a radical reframing of clinical obesity is necessary for better care and policies addressing the clinical disease of obesity. He told us:

“A disease is defined by present illness, not the risk of future illness. Clinical obesity is a chronic, systemic illness characterized by alterations in the function of tissues, organs, or the individual, due to excessive or abnormal adiposity.”

Implicit Denial That Obesity Is a Disease

It is not hard to find signs of implicit denial that obesity is actually a chronic disease – one that requires actual medical care. Writing in the Telegraph, William Sitwell says:

“Fat people are costing us all billions. It’s time to get tough. I used to think the obese should be left alone – but they’re beginning to crush us.”

This rant would be absurd if Sitwell were talking about cancer. People would laugh him off the stage of public discourse. But when obesity is ill-defined as a disease in its own right, it leaves room for buffoons like him to spout off like this. He is free to act like obesity is nothing but evidence of bad behaviors that lead to other diseases.

Unease About a “Radical Reframing”

This should be easy. The need for better defining clinical obesity is plain enough. But building consensus is always difficult. As we talked to experts from all over the world, we heard a bit of unease. We should use “BMI plus other criteria” was something we heard frequently. Some asked “Does a person with a very high BMI (for example 60) not have clinical obesity if they present with no other symptoms or impairment?”

These are all good questions. The report of the Lancet Commission on Clinical Obesity is under review for publication – soon, we hope. The conversations it prompts will mark a key milestone in advancing the medical understanding of obesity.

Click here, here, and here for further perspective on the work of this Lancet Commission.

Piazza San Marco in Venice Moonlight, painting by Ippolito Caffi / WikiArt

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May 15, 2024